releasing: update for the new release process
A few things have changed:
- Meson is used instead of autotools
- Wayland and Weston releases are not synchronized anymore
- Artifact deployment happens via wayland.freedesktop.org's Git repo
While at it, also convert the file to Markdown. Instructions to locally install Xwayland/libinput have been dropped.
I haven't bothered splitting the changes into fine-grained commits. I think reading both the old and new version side-by-side should give a pretty good idea of the changes.
Some changes to release.sh
have yet to be upstreamed.